Troubleshooting Electric Trailer Brakes that Lock Up in Reverse

Updated 11/22/2014 | Published 11/21/2014

Products Featured in This Question

Dexter Electric Trailer Brake Assembly - 12" - Right Hand - 6,000 lbs

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$98.08

Hook Probe Circuit Tester

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$12.41

Question:

I just replaced the complete brakes on my trailer, new backer plates etc., I just had to bolt on and hook up the wires. The same way they were. I replaced them because the brakes were locking up in reverse, I still have the same problem. I cleaned the drums no oil or grease on braking surface or rust. So what is my problem?

asked by: Dennis

Expert Reply:

If you disconnect the trailer connector when backing up do the brakes still lock up? What I bet is happening is that your trailer reverse light circuit is shorting out to the brake output circuit which is causing the brakes to apply every time you put your vehicle in reverse.

If you have a great emergency brake and the ability to block your back wheel what I would recommend you do is test the brake output circuit of your vehicle with a circuit tester like # PTW2993 when your vehicle is put in reverse and the brakes of the vehicle are released. This will be the 5:00 pin of the connector. If this pin has voltage when the vehicle is in reverse and the brakes released then the short is on the truck side of the wiring. If not, then the problem is on the trailer.

Either way you will want to closely inspect the insides and outside of the connectors looking for any corrosion or exposed wire that could be causing the short and fix as necessary. If nothing is there you will need to trace the wiring back up till you find the short.

expert reply by: Jameson C